One idea I had a while ago was that you could use these for saving energy by targeting exposed skin surfaces only. This would be particularly useful for offices: the office can be set to the lower temperature preferred by men, and then women can be targeted by the infrared heaters to keep them comfortable as well, so no one has to be uncomfortable while still saving energy. (It has to default to colder/male preferences because you save more energy by keeping the office as a whole at the lower temperature, and anyway, there's no such thing as an 'anti-heat beam' so you can't cool down a subset.)
Indeed, women in offices now tend to either suffer or sweater. They are solutions, but not good ones. Infrared trackers would allow one to have one's cake of attractive stylish (non-sweater) clothing while not suffering in the eating. So to speak.
If they were pervasive, they could allow institutional users to lower the temperature in their buildings a few degrees. One degree on the thermostat for a large building in New England could equate to a lot of savings in fuel.
It may surprise you but using a micro-controller and some servos is today often an easier and simpler solution than building a complex mechanism using cams and clockworks.
That sounds like a fun project, but economically impractical. When we installed panels on our roof it was cheaper to just lay them flat and buy extra panels to make up the difference, than to install them on static frames to angle them for most efficient energy generation. If static frames are not worth it, dynamic ones are definitely going to be too expensive.
Perhaps at scale, things would be different, but I doubt it.